Carburetor



M. c. MORRIS CARBURETQR Filed osta-'1o. 1925 July 24. 1928.

fliatented `luly 24', 192.8. i

y 1,671,926. UNITED' STATES- PATENT oFFicE.

IAX CYRIL IOBBS, F GASTLEBELINGHAM, IRELAND.

emplearon.

Application med october 16,1923, serial No. 667,602, and in creat nriltainoctober 21., 1922..

, The present invention relates to carburetors for internal combustion engines, and more'especially to such as are intended for use in Aconnection with motorroad vehicles.

'- 5 The principal object of the invention-is to provide a carburetor which is of simple and robust' construction, which does not involve any ccmplicatedor delicate'elements giving rise to ditlicultiesnor expense in man-` ufacture, or which are"easily damaged or put out of adjustment in use, and which offers 'a lvery complete atomization of tlreliquid fuel and also all thechief qualities desirable in a carburetor for road vehicle 1.5 Work including the provision of a substantially uniform proportion of fuel and air as the throttle valve is progressively opened. A further obj ectis to attain the desired uniformity of mixture proportions'. without l calling for any manual operation during running beyond that 'of opening or closing the throttle valve, and yet another object is to provide a carburetor. of' this nature which `embodies simple' means providing for semipermanent adjustment o the carburetor for different fuels or for engines of dilferent sizes, or for different engine or atmospheric conditions. Y

` With these objects in View, ar-preferred.

construction ofthe carburetor comprises a casing, a main passage therethrough, successiveportions of thispassage constituting respectively a main air inlet, a mixing chamber and a mixtureoutlet, a throttle valve consisting of a plunger reciprocable across the said passage, a fuelv nozzlelocated in a.

well-shaped chamber 1n the casing oppo` y site fto the inner end ofthe plunger throttle valve, and al tubular member attached to `thefuel nozzle and within the well-shaped braces also, according toone feature of the present invention, the feature that the tubuT lar member which is a loose fit in the Wellshaped chamber and upon the fuel nozzle, is provided on the engine side with a wide' longitudinally disposed Vopening `Wchich is progressively exposed to the mixture outlet side of the main passage as the -throttle valve is opened. Moreover, according to an other feature of the invention,- a supplementary air supply is` also provided by means of a conduit alfording 'communication' solely between the said well-shaped chamber and the 'exterior of the carburetor and unthe 'throttle valvejand-,litting loosely overl der the control of a manually operated` Figure 2 is a vertical section onvthe line 2 2 of/Fi'gu're 1.

lFigure 3 is a fragmentary vertical s'ection on the line 3-3 of Figure 2.

' Figuresll and\5 are respectively a front view and a side view of the plunger valve and, tubular member detached from the carburetor. Y

Referring now to these drawings, 1 is the main casting of the carburetor, the float chamber 2 being'indicated indotted lines. 3V is the 'inlet for the air and 4 the outlet for the mixture. 5 is the fuel nozzlelocat'ed in a,- vertical well '6'A in the main casting. For mounting it in position it is provided with an enlarged lower end 7 which is maintained against` the shoulder 8 'by a short backing' plug 9 which is screwed into the internally threaded bore *10 in the' casing and is provided with a central orifice 11 for passage of the fuel to the nozzle.

fuel nozzle has been mounted in position and 14 is another screwed plug giving access tothe fuel passage 12 for cleaning etc. 15 is the main'airval've constituted by a-pise to the mixin'gchamber in. the'vertical bore 16 by any suitable .actuating mechanism. The lower end of this iston valve is preferably cut away obliquely so asto present an inclined face 17 fon the. air side. The piston. carries .a downwardlyfextending tubular 13 isa screwed, vplug serving to cl e the bore 10 after the ton adapted to be reciprocated transversely member 1e which fits -loosely in the annumspace between the fuel nozzle 5 and the bore 6. This tubular member is shown in part section in Figure l and in side elevation Figure 2 also,separa tely in elevation in Figures 4 and 5.. 19 isa wide .longitudi nally dis osed openingen .the engine m'de 1 1fA of the tu iilar member this being formed by cuttingvawayfthe Vlower part o'f this member Y l on that side, leaving a strip or bar for guiding and strengthening purposes. 21 is a circumferential .groove around the'piston2 dotted lines at 22 and 23 respectively on Figures 4 and 5. Figures 2 and 3 illustrate another arrangement'for the same purpose whi h is effective throughout the greater range of throttle opening and which embodies an automatic control valve. rangement comprises a ball 24 located in a vertical bore 25 and normally resting on a transverse pin 26. The bore 25 is incommunication with the outer air through the open lower end 27 thereof and also through one or more side openings 28, and it is also in communication throughan orifice 34 with a transverse bore 29 which is in communication with the jet chamber 6. The bore 29 is also in communication through an orifice 30 with another bore 31 which is internally Screw-threaded to receive a screwed plug 32.

By this means the .orice 30 may be partially or wholly occluded by screwing the plug inwards in the bore 31.

The construction of the tubular member, as hereinbefore described, tends to give ver complete atomization ofthe fuel for the fo lowing reason. At all openings ofthe throt- ,tle valve (beyond the very first small extent of opening movement while the solid part of the tubular member 18 adjacent to the plunger is within the mouth of the wellshaped chamber 6) the fuel issuing from the orifice at the top end of the nozzle 5 is shielded on the air entry side from the entering main air stream,fwith the, result that the solid it of fuel is not 'at first deflected but trave s upwards and impinges against the roof and side walls of the tube, sol as to receive a preliminary brealn'ng up action after which it is thrown downwards an forwards through the o ening 19 inl the member, and .is then caug t up inthe main air stream, which is in a whirling condition, owing to. its having been deflected under the bottom of the plunger, and from the surfaces of theA tubular member andthe side g walls of the main passage. The main opening 19 is of quite substantial width relative- 1y to the area available for fuel youtlet from the nozzle and saidopening is 'intended to permit of the suction in. the mixmg chamber in the region of the mouth of the wellshaped chamber be' fully effective on the fuel outlet orifice. .aid opening v19 is. in

vno sense a measuring opening or valve, for

controlling the amount of liquidw fuel `delivered into the main air Thus 'the This arfrom the strip or bar 20 left for uiding or strengthening purposes) as being ormed by slicing away about half of vthe cylindrical body of the 'tube to leave a tongue on the aii1 entry side which functions only or prinvc ipally to shield the fuel stream from the entering air.

ment of the straight-through type of carburetor with a plunger valve moving across the main passage and'in the region` ofthe fuel nozzle, a very simple and inexpensive construction is provided. This type of carburetor, however, has the well-known dis- .advantage that at small throttle openings when the speed of air passing beneath the plunger is very high relatively to the total It will lbe observed that by the employvolume of air passing in other words, when there is a strangling action onl the air, there is an unduly high proportionate degree of suction upon the fuel, this degree progressively lessening as the plunger valve is opened and it will lbe noted that-the present invention lashereinbefore described pro-v vides for correction of this disadvantage by lessening the proportionate degree. of suction at small throttle openings by permitting inleak of air 'from the exterior of the carburetor intoy the well-,shaped chamber 6.

For purposes of description,l it will be convenient to consider separately 'the two' methods of admitting outside air into the welll-shaped chamber which are illustrated in the drawings, namely the method which includes provision of the screw plug valve 32 and the methodwhich includes provision of the automatic ball valve'24. Considering first the latter, and disregarding the valve^ 105 32 and air inleakv orifice '30, with small throttle opening and 'slow running of the engine, the ball 24 will be retained by gra.V- ity in the position shown inV full lines so that outside `air can enter freely through the orifices '28 and 34 and the bore 29 into the well-shaped chamber from 'whence ,itl

passes upwards and debouches into the mai-n air stream at the mouth of the well-shaped chainber in the immediate'region or in advance of the fuel outlet oriice. The degree 5 of lsuction due to the engine which in the absence of the controlling air admitted would iis be effective on the fuel, is reduced owing 'to'` the strangling action of the. throttle on themain air stream is V reduced the suction at the mouth ofthe well-shaped chamber increases, although theratio of this suction to the total volume ofair passing decreases with opening of the throttle. When a certain degree of suctionis attained, the ball valve 24 is drawn u Iinto the ositionshown in dotted lines in igure 2, t us closing the orifice 34 Lenses v yand thus cutting of communication between the well-shaped chamber andthe outer air. This valve thus acts to reduce the propor' tionate degree of suction'upon the fuel during a certain extent of opening movement of the throttle and beyond this lextent of opening removes the correction thus provided, that vis to say, whenit is no longer necessary or of such degree of importance.

Considering now the method of admitting air which embraces the screw plug valve 32, and disregarding the opening 34 'controlled by the ballvalve, outside airis admitted through the end 33 of thescrewed ibore 3 1, that partvof opening which is uncovered by the plug 32, and bore 29 to the well. The .amount of air admitted is thus depend-4 ent upon the position of the plug 32 in relation to the orifice 30, which position may be. varied at will. The effect ofthe entering air is as. before to reduce the proportionate degree of suction upon the fuel and in this case l the vcorrection applied is effectivethroughout the Whole range of throttle opening. It is to be noted,however, that the correcting effect will be proportionately reduced as the throttle valve isopened and the total volume of air'passing becomes progressively greater compared with the maximum amount of air which can pass through the restricted opening 30. O

It is preferred, however, to employ the two methods just described in combination in one structure as illustrated in the drawings,- and in a carburetor as so constructed i the main correction is effected by the ballvalve arrangement, the other larrangement of the plug'32 serving as a ine adjustment which can be set to determine the point at which thev ball valve operates, and moreover serving as a means for semi-permanent ad justment of the carburetor for different lfuels or for engines of different .sizes or for diderent engine or atmospheric conditions. f

The object of the groove 21 is to provide a small by-pass for air pastthe throttle valve to reduce the extremely excessive suction, on the fuel orifice during the very first movement of openin of the throttle valve, and it will be noted t at as soon as the valve has been very slightly raised the groove 21 bej cmes enclosed within the bore 16 and is no longer effective as a by-pass for air.v

In this connection it 1s to be noted that, the tubular ,A member 18 being a designedly loose fit within the well-shaped chamber 6, the suction is available at the jet, and fuel is actually drawn up through the annular space .between the said tubular member and the wall of the well-shaped chamber evenat very small opening of the throttle valve before the solid portion of the tube is withdrawn from the mouth of the said member. Parts 22 and passages 23 are shown in dotted lines in Figures 4 and 5 merely for the purpose of showing how additional ai supplies may o r may vnotbe provided. One .of these alter natives embraces a small diameter passage 23 bored from the upper end of the throttle valve into the interior ofv the'tubular member, and another alternative embraces a small orifice 22 formed in the,tubularv member on the air entry side. No means for rendering such passage or orifice positively ineffective are described :but it will be readily understood that for practical purposes they become rapidly ineffective as the throttle valve is raised. v

Moreover, as .shown in the drawings it is preferred to leave the tube 18 solid for a short distance below the throttle valve, this portion blocking lthe mouth of the well at extremely small throttle openings and so strangling to some extent the suction on l the fuel at such openings.

lAs previously statedv however, the tubular anv member 18, is aloose fit'both over the fuel nozzle' 5,( and within the well 6 so that at the extremely small throttle opening just refered tothe effect of the complete portion of the tubular member above the opening 19 is onlyto strangle and not entirely to cut oif the passage of .fueln i What I claim and desire to secure by Letters Patent of the United States is 1. In a carburetor, the combination of ,a j

plunger valve movable diametrically across the main passage, said plunger valve having a circumferential groove thereon adapted to permit an' inleak of air` through the main passage past-'the said valve when the latter is in theclosed position and during a, small degree of opening movement thereof, and to be enclosed by the casing on continued opening movement o-f thesaid valve, la tubular member carried Aby the plunger valve, a well-shaped'chamber formed in the casing opposite to-the said valve, and a fuel nozzle `disposed axially in the said well-shaped chamber, the said tubular member being movement of the said plunger valve loosely adapted to reciprocate synchronously with within the annular space between the wall of the well-shaped chamber and the -fuel nozzle and beinglprovided on the engine side thereof with a wide longitudinally disposed opening which Ais progressively exposed to the main passage 'on the engine side as the throttle valve is progressively opened.

2. In a carburetor having a plunger' throttle valve movable diametrically across the main passage, the combination of a tu-l bular member carried b the plunger valve, a well-shaped'chamber ormed in the casing,

opposite to the said valve, a fuel nozzle dis' posed axially in the said well-shaped chamber, the said tubular member being adapted to reciprocate, synchronously with movement of the said plunger valve loosely within. the annularspace between vthe wall of the welli ing opposite said valve; a fuel nozzle disposed axially of said Well-shaped chamber,

at the mouth of i ber. v v i 3. Inl a carburetor having a plunger shaped chamber and-the fuel nozzle and being pro vided on the engineside thereof With a Wide longitudinally disposed opening 'which is progressively exposed to the main passage on the engine side' as the throttle Valve is progressively opened, a conduit affording communication solely between the said Well-shaped chamber and the exterior of the carburetor, and an automatic valve adapted normally to occupy a position giving free access of air through said vconduit and to be actuatedfby suction to obstruct the passage of air through said conduit on -a redetermined degree of suction being attained the said Well-shaped memthrottle .valve movable diametrically" across the main passage thereof, the combination of a vWell-shapedtchamber formed -in the casa tubular member carried by said plunger valve, said tubular member bein-g adapted to reciprocate synchronously with the movement of said plunger valve loosely within valve is progressively opened; conduit means l.

affording communication solely between said Well-shaped chamber and the exterior of the carburetor; two openings communicating to the exterior of the carburetor therein; manually operable means for adjusting the eective areavof one of said openings; and an automatic valve adapted normally to freely admit air through the other of said openings and, to be actuated by suction to obstruct .the last mentioned opening on a predetermined degree of'suction being attained inthe main passage at the mouth of the Well-shaped chamber.

MAX CYRIL MORRIS. 

